1. Field of the Invention:
This invention relates to the protection of antennas employed in conjunction with sophisticated communications equipment, in particular military communications equipment. By enclosing antennas within shields known as radomes, significant protective attributes can be developed. Radomes are used to protect antennas from adverse environmental effects; to provide a specific geometry, as would be necessary in air or water craft; and to avoid detection by electronic sensing equipment through absorption or scattering of the electromagnetic radiation employed by the sensing equipment. With the advent of modern threat levels employing high power lasers capable of producing electromagnetic radiation of sufficient intensity to melt most types of metals and some ceramic materials, a radome capable of protecting antennas from the high thermal fluxes associated with high power lasers is required. This invention relates to radomes providing that protection.
2. Description of the Prior Art:
The concept of radomes is not new in the art. The protection afforded antennas has varied from a simple coating designed to resist the adverse environmental effects likely to be found in a hostile military situation to a radome designed to prevent detection of antennas by sophisticated electronic sensing equipment. None of the prior art examined, however, addresses the problems associated with laser damage or destruction in a hostile environment.
In U.S. Pat. No. 3,871,739, there is disclosed an improved protective window used to protect against high energy radiation sources. This invention relates to reflecting the infrared radiation while transmitting visible light. The invention is directed to preventing localized overheating which can occur due to absorption rather than reflection of high energy infrared radiation. The absorption is due to dust or dirt which can collect on the window. This invention is concerned with improving the reflective characteristics of the protective window as the means for preventing overheating and does not suggest a solution to the problem of providing continuing protection to antennas which require opaqueness to high power laser irradiation and transparency to microwave irradiation.